Finasteride inhibits 5 alpha reductase
Finasteride is FDA approved for the treatment of male pattern hair loss at a dose of 1 mg and FDA approved for the treatment of male prostate enlargement (a condition called benign prostatic hypertrophy) at a dose of 5 mg.
The drug works by inhibiting an enzyme known as "5 alpha reductase type 2." This enzyme helps covert testosterone (T) to dihydrotestosterone (DHT). By blocking this pathway, DHT levels are lowered in the scalp by about 60 % and bloodstream by 70 %. Topical finasteride is also be an option to treat male pattern hair loss but good studies have yet to be done and I am not yet convinced either way.
Dr. Jeff Donovan is a Canadian and US board certified dermatologist specializing exclusively in hair loss. To schedule a consultation, please call the Vancouver office at 604.283.9299